Trace Metals in High Elevation Forest Soils in Maine Sarah Hayes (email@example.com), Samantha Langley-Turnbaugh (firstname.lastname@example.org) Department of Environmental Science, University of Southern Maine, Gorham, Maine INTRODUCTION Trace metals in mountain ecosystems of the northeastern United States have received considerable attention in recent years as researchers examine the effects of atmospheric deposition on the health and function of forests.1,2,3,4 High elevation soils are particularly sensitive to changes in atmospheric chemistry due to higher deposition of pollutants by wet and dry deposition, interception of wet cloud moisture, the formation of rime ice, and the tenacity of highly organic soils to retain metals. Forest floor materials can accumulate trace metals due to the strong affinity of soil organic matter for these metals.4,5 Studies by several authors suggest that trace metals may be accumulating at a rate of 20 to 30 mg/m2 yr in the Northeast and predict the amount of metals in these forest floors will double in 30 to 59 years.3,6 Trace metal input to soils may decrease phosphate availability, and several trace metals inhibit decomposition and essential ecosystem recycling processes.7,8 The purpose of this research project was to assess concentrations and spatial and temporal changes in trace metal concentrations on six mountains in Maine. • METHODS • Six of the highest mountains in Maine were sampled in this and earlier studies: Old Speck (1270 m), Goose Eye (1180 m), Saddleback (1256 m), Bigelow (1263 m), White Cap (1111 m), and Katahdin (1606 m). • Mineral and organic soil were sampled from the base of each mountain, at approximately every 304.8 m, at tree line, and at the summit if adequate soil was present. • These samples were digested using EPA methods 3050 and 3051, and analyzed for trace metal concentration using an ICP-AES. • RESULTS • MINERAL SOILS • In general, there was a slight increase in trace metal concentration with elevation, with a few exceptions. • Co and V concentrations in mineral soils consistently decreased with elevation. • On Saddleback Mountain (the only ski mountain sampled), and on Goose Eye Mountain (the westernmost mountain), all trace metal concentrations except Pb decreased with elevation. • On White Cap Mountain, there was a dramatic increase in trace metal concentration with elevation in all metals except Ni, Co, and V. • Cd was below detection limits. • ORGANIC SOILS • On Goose Eye and Saddleback Mountains, there was an increase in trace metal concentration with elevation for all metals (except for As and Mn on Saddleback Mountain). • On Mount Katahdin (the highest mountain), there was a decrease in trace metal concentration with elevation for all metals. • On Old Speck, Bigelow, and White Cap Mountains, trace metal concentrations were variable with elevation (some metals increased with elevation, and some decreased with elevation). • Pb and V concentrations increased with elevation on all mountains except Mount Katahdin. • Cd concentrations were detectable in organic soils, and were not detectable in mineral soils. • Pb, As, and Cd concentrations exceeded EPA action limits on Saddleback and White Cap Mountains. Arsenic concentrations also exceeded these limits on Goose Eye and Bigelow Mountains, Cd also exceeded these limits on Bigelow Mountain, and Pb also exceeded these limits on Goose Eye and Old Speck Mountains. • TEMPORAL CHANGES • All trace metal concentrations in organic soils increased since 1996 on Goose Eye, Old Speck, Saddleback, and White Cap Mountains. • All trace metal concentrations in organic soils decreased since 1996 on Bigelow Mountain (except for Zn) and Mount Katahdin (except for Cd). • Pb concentrations decreased from 1979 to 1996 on all mountains, and then increased since 1996 on all mountains but Katahdin (current study Pb concentrations were higher than 1979 Pb concentrations except on Mount Katahdin). View from Bigelow Mountain’s West Peak (1263 m), showing an alpine tundra community scattered amongst the rocky summit • OBJECTIVES • To report the concentrations of trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, V) in high elevation organic and mineral soils of six mountain ecosystems in Maine. • To compare collected data with samples collected in 1979 and 1996 in the same locations to evaluate temporal changes. • To determine the influence of elevation on forest floor trace metal concentration. Goose Eye Mountain Map of Maine and sampled mountains Goose Eye Bigelow Old Speck White Cap Saddleback Katahdin View of Flagstaff Lake and alpine tundra from Bigelow Mountain • SIGNIFICANCE • Trace metals deposited in forest soils can accumulate in plants through root uptake; high concentrations could affect the health of forests. • Ecosystems at and near the tops of mountains, such as alpine tundra, are most vulnerable. • ● These ecosystems are already fragile and are most exposed to • atmospheric deposition and extreme weather. • Accumulation of trace metals poses a problem to herbivores that browse the leaves of trees and other plants, such as moose. • ● There is the risk of ingesting metals that may be present due to root • uptake, as well as trace metals atmospherically deposited directly onto the surface of the leaves. • There has been a health advisory issued for moose liver and kidney consumption because of high cadmium levels. 9 • ● Some members of the Passamaquoddy tribe in Maine regularly consume • these organs. • ● Cadmium is a probable carcinogen in humans.
Trace Metal Concentrations in Mountain Soils (mg/kg) nd = not detectable Goose Eye Old Speck Saddleback Bigelow White Cap Katahdin • MAJOR POINTS: • General increase in trace metal concentrations with elevation in mineral soils. • All metal concentrations increased over time in organic soils on all but two mountains. • Pb concentrations increased with elevation in mineral soils on all mountains, and in organic soils on all mountains except Katahdin. • Pb, As, and Cd exceeded action limits in organic soils on several mountains. Acknowledgements: University of Southern Maine Summer Undergraduate Research Fellowship Maine Center for Toxicology and Environmental Health Lynn Lovewell Mark Willis Amber Hardy References: 1Johnson, A.H., T.G. Siccama and A.J. Friedland. 1982. Spatial and temporal patterns of lead accumulation in the forest floor in the northeastern United States. J. Environ. Qual. 11:577-580 2Friedland, A.J., A.H. Johnson and T.G. Siccama. 1984. Trace metal content of the forest floor in the Green Mountains of Vermont; spatial and temporal patterns. Water Air Soil Pollut. 21:161-170 3Friedland, A.J., and A.H Johnson. 1985. Lead distribution and fluxes in a high elevation forest in northern Vermont. J. Environ. Qual. 14:332-336 4Moyse, D.W., and I.J. Fernandez. 1987. Trace metals in the forest floor at Saddleback Mountain, Maine in relation to aspect, elevation, and cover type. Water Air Soil Pollut. 34:385-397 5Brummer, G., and U. Herms. 1982. Effects of accumulation of air pollutants in forest ecosystems. In B. Ulrich and J. Pankrath (eds). D. Reidel Publ. Co., Boston, MA, p.233. 6Andresen, A.M., A.H. Johnson and T. Siccama. 1980. Levels of lead, copper, and zinc in the forest floor in the northeastern US. J. Environ. Qual. 9:293-296. 7Ekenler, M., and M.A. Tabatabai. 2002. Effects of trace elements on beta-glucosaminidase activity in soils. Soil Biol. Biochem. 34:1829-1832. 8Kaste, J.M., B.C. Bostocik, A.J. Friedland, A.W. Schroth and T.G. Siccama. 2006. Speciation of gasoline-derived lead in organic horizons of the northeastern USA. Soil Sci. Soc. Am. J. 70:1688-1698 9Department of Health and Human Services, Agency for Toxic Substances & Disease Registry, http://www.atsdr.cdc.gov/toxprofiles/tp5-c7.pdf 10SSL—US Environmental Protection Agency, Soil Screening Guidance, May 1996